1. Field of the Invention
The present invention relates to an image data transmission system and method in which mobile vehicles equipped with transceivers, i.e., mobile transceivers, are used as a transmission line for transmitting image data to respective stationary transceivers.
2. Description of the Prior Art
An image data transmission system for a conventional electronic advertisement panel is disclosed in Japanese Unexamined Patent Publication No. 4-55513 and is described briefly below. FIG. 1 is a block diagram of a conventional image data transmission system schematically illustrating transmission in a subway yard. The system includes an information transmission center 1 having a production system A and a transmission system B. The production system A includes a character information production system 2, an image and sound production system 3, and a production console 4 to which the character information production system 2 and the image and sound production system 3 are connected. The production console 4 is connected to a transmission selecting console 9 in the transmission system B and to a monitor 5.
The transmission system B comprises a converter 6, a decoder 7, and a head end device 8 to which the converter 6 and the decoder 7 are connected. The transmission selecting console 9, connected to the head end device 8, selects and transmits information. A modulator 10 is connected to the transmission selecting console 9. An E/O dependent exchange device 11 is connected to the modulator 10 and to an O/E dependent exchange device 16 in a station supervisory center 15 through an optical fiber, and an automatic program controller 12 is connected to the transmission selecting console 9. The transmission selecting console 9 is also connected to the monitor 5.
The converter 6 receives radio waves from an existing television broadcasting station 13. The decoder 7 converts information entered at a newspaper company and news agency 14. The station supervisory center 15 in each railroad station comprises the O/E dependent exchange device 16 connected to the E/O dependent exchange device 11 in the information transmission center 1 through the optical fiber, a distribution supervisory console 17 connected to the O/E dependent exchange device 16, an image distributor 18 connected to the distribution supervisory console 17 to distribute advertisement data to respective electronic advertisement panels 19a and 19b, and a monitor 19c, including a video projector or the like, in the subway yard. An inductive wireless information transmission system 20 is connected to the image distributor 18 and the distribution supervisory console 17 to transmit information to electronic advertisement panels 21a and 21b in moving trains. The distribution supervisory console 17 is connected to a monitor line 23. In this drawing, T indicates a train and S indicates a subway station.
FIG. 4 is a block diagram illustrating a second conventional transmission system including a display device 24, i.e., a signboard, a display control 25, a mobile transmitting station 26, and a fixed transmitting station 27. The display control 25 comprises a receiver 28 for receiving advertisement data transmitted from the transmitting station 26 or from the fixed transmitting station 27, a transmitter 29 for transmitting information to the mobile transmitting station 26 or to the fixed transmitting station 27, a data processor 30 for processing the received data, a memory 31 for storing the processed data, and a control section 32 for controlling the receiver 28, the transmitter 29, the data processor 30, and the memory 31. The data is transmitted by means of radio waves or light. The display device 24 and the display control 25 constitute an electronic signboard device 36.
FIG. 5 is a block diagram illustrating a configuration of the transmitting station 26 or the fixed transmitting station 27 of the second conventional data transmission system. In this drawing, there are shown a transceiver 38, an image data memory 39, an image data input 40, and a control 41. Compressed image data is written from the image data input 40 to the image data memory 39. The transceiver 38 reads out the contents of the image data memory 39 based on an instruction from the control 41, and then an antenna sends out radio waves modulated with the memory contents.
Data transmitted from the transmitting station 26 or the fixed transmitting station 27 is compressed image data, and data is received at the receiver 28.
The received data is restored in the data processor 30.
Data transmitted from the transmitter 29 to the mobile transmitting station 26 or to the fixed transmitting station 27 is a response signal for reporting completion of a reception or resending of a request or the like to the mobile transmitting station 26 or to the fixed transmitting station 27. The restored image data is stored in the memory 31 and its contents are displayed on the display device 24.
FIG. 6 is a diagram of the operation of a second conventional transmission system, illustrating operation with a single mobile transmitting station 26 shown in two locations. The mobile transmitting station 26 moves on a road while transmitting display information in the neighborhood of an electronic signboard device 36 installed on a roof of a building 33 or a independent electronic signboard device 36a. The transmissions change the contents of the display simultaneously or sequentially. Two different positions of the mobile transmitting station 26 are shown in FIG. 6.
As described, in the first conventional transmission system, an optical fiber is used as a transmission line for transmission of advertisement information (image information) from a transmitting means to a receiving means. This apparatus, however, requires installing optical fibers between the transmitting means and the receiving means, which is costly.
In the second conventional transmission system, advertisement information (image information) is transmitted from the transmitting means to the receiving means with a single mobile vehicle (car) used as the transmitting means that distributes advertisement information to the receiving means. The amount of advertisement information that can be stored in a memory of a car is limited, however. Therefore, if the car distributes advertisement information to a plurality of receiving means, separate cars are needed for respective receiving means. For example, in order to change advertisements in railroad stations, a plurality of cars must carry advertisement information to be displayed on the receiving means installed in the respective railroad stations, so there is a significant cost in distributing advertisements. In addition, when using a car, advertisement information may not be distributed at a desired time due to traffic conditions, creating a reliability problem.